<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<style>
.descendants * {
	display: block;
	border: 2px solid lightgrey;
	color: lightgrey;
	padding: 5px;
	margin: 15px;
}
</style>
<script src="jquery/1.10.2/jquery.min.js">
	
</script>
<script>
	$(document).ready(function() {
		$("div").find("span").css({
			"color" : "red",
			"border" : "2px solid red"
		});
	});
</script>
</head>
<body>

	<div class="descendants" style="width: 500px;">
		div (当前元素)
		<p>
			p (儿子元素) <span>span (孙子元素)</span>
		</p>
		<p>
			p (儿子元素) <span>span (孙子元素)</span>
		</p>
	</div>

</body>
</html>